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Old 16-03-2016, 22:45   #16
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Re: maintenance on masthead blocks

There is nothing I can think of more guaranteed to lead to a seized sheave than to add grease. Over time it will attract grit, salt, sand, dust, and all sorts of contaminates then turn into a paste. Plus there is a better than even chance that the grease winds up on the sails and either stains or damages them. Worse there isn't any need to do so.

Bronze bushings with a stainless pin and delrin sheaves are well proven, and inexpensive. I would also bet that the friction coefficient for them is lower than a greased sheave even with fresh grease.
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Old 16-03-2016, 22:52   #17
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Re: maintenance on masthead blocks

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Originally Posted by Stumble View Post
There is nothing I can think of more guaranteed to lead to a seized sheave than to add grease. Over time it will attract grit, salt, sand, dust, and all sorts of contaminates then turn into a paste. Plus there is a better than even chance that the grease winds up on the sails and either stains or damages them. Worse there isn't any need to do so.

Bronze bushings with a stainless pin and delrin sheaves are well proven, and inexpensive. I would also bet that the friction coefficient for them is lower than a greased sheave even with fresh grease.
I was thinking the same. If anything at all I'd give it a spray of PTFE or graphite, but other than that I'd leave it as designed. Mine is over 36 years old and it looked like it was the origional set up and it's far from seizing.
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Old 16-03-2016, 23:24   #18
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Re: maintenance on masthead blocks

Point taken. No grease. They are solid bronze and 34 years old showing no real wear. Maybe just a shot of McLube through the hole every once in a while.

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Old 16-03-2016, 23:51   #19
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Re: maintenance on masthead blocks

For the OP, do check the wear in the bushing. If they get too much clearance, the sheave can tilt off to one side a bit. This both accelerates the wear and eventually the rim of the sheave contacts the sides of the sheave box, greatly increasing frictional losses. If this is the case, pressing the old bushes out and new ones in is a DIY job if you have a decent sized vise or a small press available. The bushes can be purchased at any seal and bearing shop, and they are inexpensive.

As to lubrication, well, Oilite scintered bronze bushings do pretty well on their own for a while, but seem to loose lubricity over time. Unlike some of the posters upthread, I've used small amounts of marine grease o n the pins on all such sheaves for several decades, and not had the horrible results posited. In fact, they have thrived! YMMV.

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Old 17-03-2016, 00:11   #20
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Re: maintenance on masthead blocks

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Call zephyr works and get some new delrin sheaves. The wire one needs to be replaced anyway, and the amount of time it will take to really clean those properly isn't worth it.
+1 for this.

I had 4 new delrin sheaves made by zephyr for $100. All have self lubricating bearings and will last a lifetime. Just mail in your current sheaves, pin and spacers if any and they will custom machine new ones based on your halyard size and current sheave masthead size.
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